Make a Little Magic

Magic happens in The Sorcerer’s Apprentice. How could it not when Balthazar Blake (Nicolas Cage), a modern-day master sorcerer, defends a city against the forces of darkness embodied in his rival Maxim Horvath (Alfred Molina)? Of course, he can’t do it alone. He needs a geek. A young guy named Dave Stutler (Jay Baruchel) becomes, yes, the sorcerer’s apprentice. It all happens in Manhattan. At least on screen. The real magic happened at Double Negative, Asylum, and other visual effects studios under the supervision of veteran VFX supervisor John Nelson. View Clips of the Movie Here!

“Originally, the work was divided just between us and Asylum,” says Adrian De Wet, visual effects supervisor at Double Negative (Dneg). “But, the volume became so large we had to get other people involved.” In fact, Dneg subcontracted some of its work to Ghost VFX in Copenhagen, Denmark, and One of Us, a boutique facility in London’s Soho district.

Cleanup

A crew at Dneg, which included an average of 150 people, finished close to 400 shots that entailed a wide range of effects, from 3D creature shots to simple wire removals. “I think we worked on about 14 separate sequences,” De Wet says. “But, the flagship was the Fantasia sequence.”

In this sequence, Dave has invited his girlfriend to his place, which is live/work space underground. “It’s a typical teenage guy’s room,” De Wet says. “It’s a dump.” So, Dave decides to use some magic that Balthazar has taught him to tidy up in a sequence that is an homage to the original Fantasia.

“Dave brings mops and sponges in the sink to life,” De Wet says. “Dirty plates teleport to the sink. But it goes horribly wrong fairly quickly.”

Before shooting the scene, director Jon Turteltaub gave the artists at Dneg the skeleton of a story. “We didn’t get storyboards,” De Wet says. “We got a handful of story beats and that was it. So we storyboarded the sequence at Dneg and went straight into previs. Then, we spent months in pre-production getting the previs nailed and getting the story right.”

De Wet describes the set as looking like an underground subway-car turntable with stone walls and a vaulted ceiling—gothic industrial. The crew filled the set with hundreds of mops, brooms, cloths, and sponges. And water, because when everything goes wrong, flooding happens.

“The special effects guys built a rig that enabled us to fill the set with ankle-deep water,” De Wet says. “So when Dave runs through the water, the splashes are practical. But, the splashes from the props are CG.”
To add the magical mops, brooms, and other props to the scene, Dneg employed puppeteers who wore green spandex suits while holding mops and brooms. “We intended to paint out [the puppeteers] later,” De Wet says. “But, of course, that never works because inevitably you end up doing things differently. So, although we used some of the practical props in the background and extreme foreground, most of the animated props in the sequence are CG.”

Dneg’s crew photographed hundreds of props on set, and then built digital replicas back at the studio. “We documented them meticulously,” De Wet says. “We had libraries with 18 types of mops, 15 different sponges, corn brooms, push brooms, four or five types of spray bottles…. I think we had props in the high 60s or 70s in any one shot.”

Animators painstakingly hand-animated each prop in every shot, even the background props. “We couldn’t just have them do a generic cycle,” De Wet says. “Everything had to have character. Jon Turteltaub is into gags and character and comedy and feeling. He wanted all the objects to have personality. Nothing just drifts. Everything comes to life, is playful, and interacts with everything else.”

Animators would create the basic performances and then once the director approved the action, the simulation artists would start their work. Each tendril of the mops moved using Autodesk Maya’s NCloth simulation. Dneg’s proprietary fur simulation tools moved the bristles of the brooms. And all the mops interacted with CG water. “What made it really hard was that we had to match the practical water splashes,” De Wet says. For fluid simulation, the studio used its proprietary Squirt solver.

All told, the sequence was approximately four minutes long. “It took lots of time and resources to get this on the screen,” De Wet notes.

Bullish Effects

The other sequences Dneg created for the film weren’t as lively, but each had its particular problem to solve. During a final battle at the end of the film, for example, the Wall Street bull comes to life and charges through downtown Manhattan, destroying cars as it stampedes down the streets.

The challenge was that the director wanted the bronze bull to remain a rigid metal. “That meant we couldn’t incorporate the realism of muscle and elastic skin stretching that you usually get with 3D characters,” De Wet says. “We made it rigid metal.”

When everyone realized the metal bull looked too robotic, though, the artists added a few muscles and skin jiggles. “We kept the bronze look of the surface,” De Wet says. “But, we allowed muscles to behave like muscles.”

Also during the final battle, a ghostly spirit of the evil Morgana materializes, so Dave and Balthazar must fight with her. The main challenge for this sequence was in finding the look the director had in mind. “His brief to us what that she had to look ghostly and ethereal, but that she shouldn’t look like a ghost,” De Wet says. “He didn’t want a hackneyed, transparent ’70s horror-film ghost.”

With that in mind, the crew shot the sequence with actor Alice Krige in costume. Then they changed her costume—her entire being, in fact—in postproduction. De Wet explains that someone on the crew came up with the idea of making her move like a shoal of fish so that she could open up or dodge out of the way, rather than move like a corporeal human.

“We used the photographed elements of Alice as a basis for the performance by doing a body track and costume track of the plates,” De Wet explains. “And then, we basically filled it with many layers of particles that had a range of tightness or looseness.” One layer had particles fitted tightly to the body and costume track. Others had a looser motion with particles that could swim farther from the body track. The effects artists could dial the tightness and looseness of the particles in and out.

“From a technical point of view, she was an interesting creature to create,” De Wet says. “We didn’t have to build a 3D character from scratch and animate it. We basically made her out of dots, a particle simulation that took the humanoid form of her. She looked like a human, but she was made of a seething mass of stuff so she could shape-shift and move around. She didn’t walk from A to B. She could drift and change shape.”

Electric Magic

Earlier in the film, Dave entertains the girl he invited to his bunker by playing music with Tesla coils. “He produces resonance using certain frequencies that become audible,” De Wet says. “So we had to create bits of lightning between the Tesla coils.”

The artists brought a desktop Tesla coil into the studio, photographed it for reference, and studied the patterns. “There’s a searching phase and a connected phase,” De Wet. “When it’s searching, it’s noisy and crackly. When it connects, all the extraneous branches disappear and we see one alpha branch that becomes thick and hot. Then it rises and breaks, and the cycle starts again.”

With this in mind, the artists created algorithms based on L-systems within Side Effects’ Houdini to create the branching look of Tesla lightning. But, once they nailed the look, they learned they needed to time the effect to music. “So we had to almost start again to get the lightning to dance to music,” De Wet says. “It was interesting. It became artistic and creative; something more than a science experiment.”

Creating a plasma ball—a successful sorcerer’s weapon of choice, on the other hand, was more straightforward. On set, the actors held bright LEDs in their hands that cast interactive light on their faces to help the CG weapons fit more easily into the scene. Back at Dneg, the artists created the plasma balls with a mixture of 2D and 3D: 3D volumetric smoke, a 3D sphere, a noise pattern, particles that stream off the sphere, and 2D, flickering light painted in. Compositors used Dneg’s own version of Apple’s Shake to bring it all together.

“This film is about magic and sorcery, so it could have been about the visual effects,” De Wet says. “And I love doing groundbreaking effects for movies. But this film is not about that. I think some of the effects, like spectral Morgana, are highly original. But, we didn’t push the envelope with new technology never used before. Instead, we tried to come up with new and interesting ideas without necessarily using freshly invented tools. We just wanted it to look good.”

Sometimes, that’s all that matters.

Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net.